The present invention relates to an automatic vehicle location system, more particularly, to a transmitting and receiving apparatus mounted on a vehicle. Generally, the vehicle location system uses a central controller and a vehicle mounted apparatus. A global positioning system (GPS) using a satellite, and a long range navigation C(LORAN C) system using an ultra high frequency(UHF) signal represent the vehicle location system. The GPS has an advantage in that it may exactly reference a vehicle, while it has a disadvantage in that it costs a great deal and its application is limited. The LORAN C, unlike the GPS, may not exactly locate a vehicle.